This invention relates to motor vehicle drive systems. More particularly, the invention relates to the combination, hereinafter referred to as being of the kind specified, in a motor vehicle of a prime mover, a multi-speed main gearing arranged for manual ratio-changing operation, a disengageable main clutch between the prime mover and the input of the main gearing, a driver-operated main clutch control, normally a clutch pedal, and an auxiliary two-ratio gearing in series with the main gearing. Normally, the auxiliary gearing will be operated hydraulically but other forms of operation such as by pneumatic means or vacuum may be employed.
Combinations of the kind specified as already known, the auxiliary gearing normally being arranged to provide, in its higher ratio, an overall overdrive ratio.
Heretofore, the control of the auxiliary gearing has entailed a manual operation of a selector member or some over-travel movement on one of the foot operated controls of the vehicle such as the clutch pedal.
In particular, the invention has particular utility when the auxiliary gearing is of the epicyclic type in which the ratios are engaged by friction clutch means. Heretofore, such auxiliary gearings have been arranged so as to change ratio while drive is being transmitted to them and this has meant that the gears and clutches have had to be relatively large and in many smaller cars there is insufficient space to mount an auxiliary gearing of this type of conventional size.
It is an object of the invention to provide a combination of the kind specified which is applicable to smaller vehicles where the space is limited.